This article is in need of attention from a psychologist/academic expert on the subject.Please help recruit one, or improve this page yourself if you are qualified.This banner appears on articles that are weak and whose contents should be approached with academic caution

Workday shifts or shift work is an employment practice designed to make use of the 24 hours of the clock, rather than a standard working day. The term shift work includes both long-term night shifts and work schedules in which employees change or rotate shifts. [1]

Shift work is considered a risk factor for many health problems, and has many negative cognitive effects. In addition, shift work can contribute to strain of marital, family, and personal relationships.[2]

Contents

The practices and policies[3] put in place by managers of round-the-clock or 24/7 operations can significantly influence shiftworker alertness (and hence safety) and performance.

These practices and policies can be fairly obvious: selecting an appropriate shift schedule or rota, setting the length of shifts, managing overtime, increasing lighting levels, or providing shiftworker lifestyle training to help shiftworkers better handle issues such as understanding basic circadian physiology, sleep and napping, caffeine usage, social life issues, diet and nutrition, etc. They may also be more indirect: retirement compensation based on salary in the last few years of employment (which can encourage excessive overtime among older workers who may be less able to obtain adequate sleep), or screening and hiring of new shiftworkers that assesses adaptability to a shift work schedule.

Breast cancer A 2005 review of earlier studies came to the result that women whose work involve night shifts have a 50% increased risk of developing breast cancer.[4] This may be due to alterations in circadian rhythm: melatonin, a known tumor suppressant, is generally produced at night and late shifts may disrupt its production.[5] The WHO's International Agency for Research on Cancer listed "shiftwork that involves circadian disruption" as a probable carcinogen in 2007 (IARC Press release No. 180).[6][7]

UCSF neurologist Louis Ptacek, who studies circadian rhythms, genes and sleep behaviors, has been quoted: "It's not surprising, we have evolved on a planet that is rotating every 24 hours. Our internal clock is more than just when we sleep and wake. It's related to cell division and it regulates our immune systems. When we battle our internal clock, that has complications."[11]Artificial lighting may additionally contribute to disturbed homeostasis.[12]

The health consequences of shift work may depend on one's chronotype, that is, whether one is a day person or a night person, and what shift one is assigned to.

Many shift workers use stimulants such as caffeine to stay awake at work and/or sleeping pills to aid with sleep during the day. However, both are addictive and should be used with care. There is currently no research on shiftworkers and long-term use of sleeping pills.[13]

Compared with the day shift, incidents has been estimated to increase by 15% on evening shifts and 28% on night shifts.[2]

One study suggests that, for those working a night shift (such as 23:00 to 07:00), it may be advantageous to sleep in the evening (14:00 to 22:00) rather than the morning (08:00 to 16:00). The study's evening sleep subjects had 37% fewer episodes of attentional impairment than the morning sleepers.[14]

There are four major determinants of cognitive performance and alertness in healthy shift-workers. They are: circadian phase, sleep inertia, acute sleep deprivation and chronic sleep deficit.[15]

The circadian phase is relatively fixed in humans; attempting to shift it so that an individual is alert during the circadian bathyphase is difficult. Sleep during the day is shorter and less consolidated than night-time sleep.[16]

The effects of sleep inertia wear off after 2-4 hours of wakefulness,[15] such that most workers who wake up in the morning and go to work suffer some degree of sleep inertia at the beginning of their shift. The relative effects of sleep inertia vs. the other factors are hard to quantify; however, the benefits of napping appear to outweigh the cost associated with sleep inertia.

Acute sleep deprivation occurs during long shifts with no breaks, as well as during night shifts when the worker sleeps in the morning and is awake during the afternoon, prior to the work shift. A night shift worker with poor daytime sleep may be awake for more than 18 hours by the end of his shift. The effects of acute sleep deprivation can be compared to impairment due to alcohol intoxication, with 19 hours of wakefulness corresponding to a BAC of 0.05%, and 24 hours of wakefulness corresponding to a BAC of 0.10%.[17] Much of the effect of acute sleep deprivation can be countered by napping, with longer naps giving more benefit than shorter naps.[18] Some industries, specifically the Fire Service, have traditionally allowed workers to sleep while on duty, between calls for service. In one study of EMS providers, 24 hour shifts were not associated with a higher frequency of negative safety outcomes when compared to shorter shifts.[19]

Chronic sleep deficit occurs when a worker sleeps for fewer hours than is necessary over multiple days or weeks. The loss of two hours of nightly sleep for a week causes an impairment similar to those seen after 24 hours of wakefulness. After two weeks of such deficit, the lapses in performance are similar to those seen after 48 hours of continual wakefulness.[20] The number of shifts worked in a month by EMS providers was positively correlated with the frequency of reported errors and adverse events.[19] A study conducted by Defense Research & Development Canada found that "with respect to sustaining cognitive performance in the face of nocturnal alarms, clearly schedule 4 [24/72] is the best schedule and schedule 5 [another schedule with 24 hour shifts] is the second best." The study also compared three schedules with day and night shifts, and found the deleterious effects of multiple night shifts to be greater than those associated with long shifts.[21]

Though shift work itself remains necessary in many occupations, through various methods employers can alleviate some of the negative health consequences of shift work. The United StatesNational Institute of Occupational Safety and Health recommends employers avoid quick shift changes, permanent night shifts, and several days of work offset by several days off. Employers should also attempt to minimize the number of consecutive night shifts, long work shifts and overtime work. Having a regular, predictable schedule can also diminish the negative health effects of shift work. A poor work environment can exacerbate the strain of shiftwork. Adequate lighting, clean air, proper heat and air conditioning, and reduced noise can all make shift work more bearable for workers.[13] Also, appropriate sleep hygiene is recommended.[2]

Employees can mitigate the effects of shift work by blocking out noise at home, maintaining a regular sleep routine, and avoiding heavy foods and alcohol before sleep. Exercise in the three hours before sleep can make it difficult to fall asleep, so workers might exercise before work instead.

The behaviors and decisions made by people who work shift work affect their alertness, safety, and performance (and possibly their short-term and long-term health, although that has not been adequately studied at this time). There are a number of areas in which shift workers can implement certain fatigue countermeasures and other ways in which they can modify their lifestyles to better adapt to the realities of their work schedules.[22] These include managing what and how much they eat, managing their use of caffeine and other substances to increase alertness or induce sleep, creating a sleep-friendly environment for sleeping during the day time, avoiding drowsy driving,[23] how to nap effectively, and tips for maintaining family and social life.

Template:Ref improve section
The practices and policies put in place by managers of round-the-clock or 24/7 operations can significantly influence shift worker alertness (and hence safety) and performance.[citation needed]Air traffic controllers typically work an 8-hour day, 5 days per week. Research has shown that when controllers remain "in position" for more than two hours, even at low traffic levels, performance can deteriorate rapidly, so they are typically placed "in position" for 30-minute intervals (with 30 minutes between intervals).

These practices and policies can be fairly obvious: selecting an appropriate shift schedule or rota and using an employee scheduling software to maintain it, setting the length of shifts, managing overtime, increasing lighting levels, or providing shift worker lifestyle training to help shift workers better handle issues such as understanding basic circadian physiology, sleep and napping, caffeine usage, social life issues, diet and nutrition, etc. They may also be more indirect: retirement compensation based on salary in the last few years of employment (which can encourage excessive overtime among older workers who may be less able to obtain adequate sleep), or screening and hiring of new shift workers that assesses adaptability to a shift work schedule.

A day may be divided into three shifts, each of 8 hours, and each employee works just one of those shifts; they might, for example, be midnight to 08:00, 08:00 to 16:00, 16:00 to midnight. Generally, "first shift" refers to the day shift, with "second shift" running from late afternoon to midnight or so, and "third shift" being the night shift. On occasion, more complex schedules are used, sometimes involving employees changing shifts, in order to operate during weekends as well, in which case there will be four or more sets of employees.

12-hour work shifts are also in use. In a modern steelworks, four sets of personnel are used, working consecutive days in one 12-hour shift (06:00 – 18:00 and vice-versa). Shift A will work days, and shift B nights, over a 48-hour period, before handing over to shifts C and D and taking 48 hours off. In the offshore petroleum industry, employees may work 14 consecutive days or nights, 06:00 – 18:00 or 18:00 – 06:00, followed by three or four weeks free. The svingskift (literally: "swing shift") in the offshore petroleum industry in Norway refers to a two-week tour during which employees work 12-hour days the first seven days and 12-hour nights the second (or vice versa).

Shift work was once characteristic primarily of the manufacturing industry, where it has a clear effect of increasing the use that can be made of capital equipment and allows for up to three times the production compared to just a day shift. It contrasts with the use of overtime to increase production at the margin. Both approaches incur higher wage costs. Although 2nd-shift worker efficiency levels are typically 3–5% below 1st shift, and 3rd shift 4–6% below 2nd shift, the productivity level, i.e. cost per employee, is often 25% to 40% lower on 2nd and 3rd shifts due to fixed costs which are "paid" by the first shift.[24]

In general, requiring workers to live on a time-shifted schedule for extended periods is unpopular, and this typically must be paid for at a premium. It is common in heavy industry, particularly automobile and textile manufacturing and is becoming more common in locations where a shut-down of equipment would incur an extensive restart process. Food manufacturing plants, in particular, have extensive cleaning programs that are required before any restart. The use of shift work in manufacturing varies greatly from country to country. Shift work is common in the transportation sector as well. Some of the earliest instances appeared with the railroads, where freight trains have clear (i.e. passenger-free) tracks to run on at night. Shift work has been traditional in law enforcement and the armed forces: for example sailors must be available to handle a vessel around the clock, and a system of naval watches organized to ensure enough hands are on duty at any time. This is shift work by another name.

Service industries now increasingly operate on some shift system; for example a restaurant or convenience store will normally each day be open for much longer than a working day. Shift work is also the norm in governmental and private employment in fields related to public safety and healthcare, such as Emergency Medical Services, police, fire prevention, security and hospitals. Companies working in the field of meteorology, such as the National Weather Service and private forecasting companies, also utilize shift work, as constant monitoring of the weather is necessary.

Much of the Internet services and Telecommunication industry relies on shift work to maintain worldwide operations and uptime.

Anttila, T., Natti, J., & Vaisanen, M. (2005). The experiments of reduced working hours in Finland: Impact on work-family interaction and the importance of the sociocultural setting: Community, Work & Family Vol 8(2) May 2005, 187-209.

Jamal, M. (2004). Burnout, stress and health of employees on non-standard work schedules: A study of Canadian workers: Stress and Health: Journal of the International Society for the Investigation of Stress Vol 20(3) Aug 2004, 113-119.

Jamal, M., & Badawi, J. A. (1995). Nonstandard work schedules and work and nonwork experiences of Muslim immigrants: A study of a minority in the majority: Journal of Social Behavior & Personality Vol 10(2) Jun 1995, 395-408.

Kivimaki, M., Kuisma, P., Virtanen, M., & Elovainio, M. (2001). Does shift work lead to poorer health habits? A comparison between women who had always done shift work with those who had never done shift work: Work & Stress Vol 15(1) Jan 2001, 3-13.

Pattanayak, B. (2002). Effects of shiftwork and hierarchical position in the organization on psychological correlates: A study on an integrated steel plant: Organization Development Journal Vol 20(2) Sum 2002, 71-82.

Sanders, K., & Nauta, A. (2004). Social Cohesiveness and Absenteeism: The Relationship Between Characteristics of Employees and Short-Term Absenteeism Within an Organization: Small Group Research Vol 35(6) Dec 2004, 724-741.

Spencer, M. B. (1987). The influence of irregularity of rest and activity on performance: A model based on time since sleep and time of day: Ergonomics Vol 30(9) Sep 1987, 1275-1286.

Srithongchai, S., & Intaranont, K. (1996). A study of impact of shift work on fatigue level of workers in a sanitary-ware factory using a fuzzy set model: Journal of Human Ergology Vol 25(1) Jun 1996, 93-99.

Tomei, G., Cherubini, E., Ciarrocca, M., Biondi, M., Rosati, M. V., Tarsitani, L., et al. (2006). Assessment of subjective stress in the municipal police force at the start and at the end of the shift: Stress and Health: Journal of the International Society for the Investigation of Stress Vol 22(4) Oct 2006, 239-247.

Welte, C. E. (1994). Day and evening staffs' perceptions of administrative expectations for humanized nursing care: A study of shift differences in a state psychiatric hospital. Dissertation Abstracts International Section A: Humanities and Social Sciences.

White, W. L. (1977). The effect of flexible working hours on absenteeism and job satisfaction, and the relationship between locus of control and utility of flexible working hours: Dissertation Abstracts International.

Williams, L., & Haskett, G. J. (1976). Employee attitudes regarding various characteristics of job opportunity and job performance across three different work-shifts at an institution for the retarded: Research & the Retarded Vol 3(4) 1976, 113-122.